The present invention relates to a magnetic coupling device on a toy vehicle, said device having a magnetic element and a fixing element, by means of which the magnetic element is fixed to the vehicle and which has a substantially dome-shaped coupling surface, which is arranged to be kept in abutment by magnetic attraction against a coupling surface of a coupling device on another toy vehicle.
In a prior-art magnetic coupling device of this kind (see SE 7301083-7), the magnetic element consists of a disk-shaped magnet with a through center hole and the fixing element consists of a metal nail with a head and a shank. The magnet is nailed to the toy vehicle by means of the nail, whose shank extends through the center hole of the magnet and whose head abuts against the magnet and presses the same to abut against the vehicle. Thus, the magnet is kept fixed to the vehicle. The surface of the nail head facing away from the magnet is dome-shaped and forms the coupling surface of the magnetic coupling device.
When two toy vehicles, each provided with at least one such prior-art magnetic coupling device, are coupled to each other by means of two coupling devices, whose magnets are oriented such that their portions facing the respective coupling surfaces have opposite polarity (north and south), the coupling surfaces of the two devices are kept in abutment against each other by the magnetic attractive force. When the magnets of the two coupling devices are oriented such that their portions facing the respective coupling surfaces have the same polarity (north or south), the coupling surfaces are instead repelled from each other. Each toy vehicle is usually provided with two magnetic coupling devices, which have different outwardly directed polarity and of which one is mounted in the front part of the toy vehicle and the other is mounted in its rear part. Therefore it is important that two toy vehicles, which are to be coupled to each other, be turned in the right direction in relation to each other in order to permit coupling. Thus, it may be difficult for small children to couple the toy vehicles.
To find a remedy for this, magnetic coupling devices are provided, which have a magnetic element, which is arranged to rotate on a shaft extending transversely of the driving direction of the toy vehicle, said shaft being supported by two arms, which project from the end of the toy vehicle. Since in this case the magnetic element can rotate, it automatically takes the correct position, i.e. such a position that its north magnetic pole is directed towards a south magnetic pole and vice versa, when the magnetic coupling device is moved towards another magnetic coupling device.
Thus, if a first toy vehicle, which is provided with a magnetic coupling device of this kind, is to be coupled to a second toy vehicle, which is provided with a magnetic coupling device, a coupling is provided irrespective of how the poles of the magnetic element in the coupling device of the second toy vehicle are oriented.
However, the above-described solution suffers from the great drawback that the magnetic coupling device can easily break if the toy vehicle is treated roughly and, for instance, dropped on the floor. The projecting arms, on which the magnetic element is rotatably mounted, can easily be snapped off.
Therefore the object of the present invention is to provide a magnetic coupling device, which solves the problem described by way of introduction while having a robust and strong design.
According to the present invention, this object is achieved by a magnetic coupling device, which is of the kind stated by way of introduction and characterized in that the fixing element inside the coupling surface has an inner cavity, in which the magnetic element is arranged to be freely movable.
In a preferred embodiment, the fixing element has a head, whose outer surface forms the substantially dome-shaped coupling surface and in which the cavity is formed, and a shank, which projects from the head and which extends into a hole in the toy vehicle and is fixed in said hole.
In another preferred embodiment, the fixing element substantially has the form of a button, which is fixed to the toy vehicle.
Advantageously, the fixing element is made of plastic material.